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Flashcards in Unit 2 Deck (53)
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1
Q

What is a homologous series?

A

A homologous series is a group of chemicals which;

  • Have the same general formula
  • Similar chemical properties
  • A gradual change in physical properties
2
Q

What are the 3 main homologous series ‘groups’?

A

Alkenes
Alkanes
Cycloalkanes

3
Q

What is the general formula for the Alkanes?

A

Cn+H2n+2

4
Q

What are the prefixes for the homologous series?

A

1) Meth-
2) Eth-
3) Prop-
4) But-
5) Pent-
6) Hex-
7) Hept-
8) Oct-
9) Non-
10) Dec-

5
Q

What are the 2 structures?

A

Straight chain and Branched

6
Q

What is an Isomer?

A

Isomers are molecules with the same chemical formula but different structural formula.
They have the same number of each type of atom but may have different physical and chemical properties.

7
Q

What are the rules for systematic naming?

A
  1. Identify the longest chain of carbons.
  2. Number the carbon so that the branches (if any) are on the smallest number of carbon possible.
  3. Any carbons which aren’t in the longest chain are part of a branch. Branches should have their name and position on the longest chain of carbons. These branches have the suffix -yl.
  4. Then put the name together, for example;
    2-methylpentane
    ‘2’ being the position of the branch and methyl being a branch of 1 carbon.
    Note: If you are systematically naming an alkene or alcohol you would put the position of the double bond (alkene) or the position of the hydroxl functional group.
8
Q

What is the general formula for the alkenes?

A

CnH2n

9
Q

What is a hydrocarbon?

A

A hydrocarbon is a compound which only contains Hydrogen and carbon.

10
Q

What is the general formula for the cycloalkanes?

A

CnH2n (the same as the alkenes)

11
Q

What is the first member of the alkenes?

A

Ethene

12
Q

How do you test for unsaturation?

A

To test for unsaturation, a chemical can be shaken with bromine solution (bromine water). The bromine solution (bromine water) will be decolourised immediately if a chemical is unsaturated.

13
Q

Which homologous series member is unsaturated?

A

The Alkenes

14
Q

What type of bonds do the cycloalkanes and alkanes have?

A

Only single carbon to carbon bonds (C-C)

15
Q

What is a addition reaction?

A

A reaction in which one molecule combines with another to form a larger molecule with no other products.

16
Q

How does an alkene form an alkane?

A

It’s possible to make alkane molecules from alkenes by carrying out an addition reaction known as hydrogenation, (an addition reaction including hydrogen/ H-H).

17
Q

What is cracking?

A

Cracking is a process when large molecules are broken up into smaller more useful ones. This process is usually carried out with the use of a catalyst, usually aluminium oxide, which allows the process to be carried out at a lower temperature.

18
Q

What are the products of cracking?

A

A smaller chain alkane and at least one smaller chain alkene is formed.

19
Q

Give an example of when cracking is useful:

A

It’s particularly useful when the fractional distillation of crude oil produces a high quantity of a large fraction which is not heavily in demand.

20
Q

What are alkenes commonly used for?

A

They’re commonly used to make polymers (plastics) and to make alcohols.

21
Q

Are alkenes soluble is water?

A

No

22
Q

What’s the first member of the cycloalkanes?

A

Cyclopropane

23
Q

What’re the properties and uses for cycloalkanes?

A

They are insoluble in water (insoluble=incapable to dissolve) but they do dissolve other chemical which are also insoluble in water, so they make good solvents. They can also be used in fuels.

24
Q

How do you calculate the mass from a balanced equation?

(Example for this question: )
66g of propane is burned in a plentiful supply of oxygen. Calculate the mass of carbon dioxide produced in the reaction. 
B.C.E: C3H8 + 5O2 ------> 3CO2 + 4H2O
Propane : Carbon Dioxide
1 mole : 3 moles
? moles : ? moles
A
  1. Write the balanced equation (balance it, if not already been balanced).
  2. Calculate the number of moles of the ‘known substance from the equation.
    N(Moles)=Mass÷GFM
  3. Use the balanced equation to identify the molar ratio of ‘known’ substance to ‘required’ substance and then calculate the number of moles of the ‘required’ substance.
  4. Answer the question by calculating the ‘required’ substance.
25
Q

What are the products for a complete combustion?

A

Carbon Dioxide and Water (CO2 AND H2O)

26
Q

What’re the products of a incomplete combustion?

A

Carbon (soot) and carbon monoxide. It still produces carbon dioxide and water but just in smaller amounts.

27
Q

What has to happen for a complete combustion to take place?

A

A plentiful/sufficient amount of oxygen has to be in the surrounding area.

28
Q

When does incomplete combustion occur?

A

Incomplete combustion occurs when a
combustion reaction occurs without a
sufficient supply of oxygen.

29
Q

How do you test if CO2 is ‘present’?

A

It will turn lime water from ‘clear’ to chalky/cloudy.

30
Q

What is an alcohol?

A

An alcohol is a carbon compound which contains the hydroxyl group.

31
Q

What is a carboxylic acid?

A

A carboxylic acid has a functional group called the carboxyl group.

32
Q

What functional group is in alcohol’s?

A

Hydroxyl

33
Q

What functional group is in carboxylic acid’s?

A

Carboxyl

34
Q

What is a functional group?

A

Functional groups are specific substituents or moieties (can be found with other molecules as well) within molecules that are responsible for the characteristic chemical reactions of those molecules.

35
Q

What happens when a carboxylic acid reacts with an alcohol?

A

When a carboxylic acid reacts with an alcohol an ester is formed.

36
Q

What is the general formula for the homologous series known as the alcohols?

A

CnH2n+1 OH

37
Q

What is the general formula for the homologous series known as carboxylic acids?

A

Cn-1 H2n+1 COOH

38
Q

What alcohol is present in alcoholic drinks?

A

Ethanol

39
Q

Name a way ethanol is produced

A

Fermentation

40
Q

Describe distillation

A

Distillation is the process of separating components or substances from a liquid mixture by using selective boiling and condensation.

41
Q

Name uses for carboxylic acids and alcohols

A

Solvents, Food and drink industry, cleaning and (alcohols) fuel

42
Q

How do you name salts from carboxylic acids?

A

Same as before (before meaning unit 1) but the ending of the salt name comes from the name of the carboxylic acid. The suffix of the acid is changed from “-anoic acid” to “-oate”. For example;
Butanoic acid+Sodium oxide —>Sodium butanoate
+water

43
Q

What is the salt name for this neutralisation:

Propanoic acid + Lithium hydroxide

A

Lithium propanoate

44
Q

Describe characteristics and uses of an ester:

A

Sweet smells, perfumes, flavourings, solvents, paints and lacquers.

45
Q

What happens when fuels burn?

A

When fuels burn they release heat energy and light energy to the surroundings in exothermic reactions known as combustion reactions.

46
Q

What is the calculation for heat energy?

A
Eh=cm∆T
(c=specific heat capacity of water 4.18 KJ KG-1 C-1)
(m=mass of water in kg) 
(∆T=change in temperature,
 final temperature-initial temperature)
47
Q

What’s the definition for a fuel?

A

A fuel is any substance which produces energy when burned.

48
Q

Examples of fossil fuels.

A

Crude oil
Natural gas
Coal

49
Q

Describe the formation of coal:

A

Hundreds of millions of years ago large trees died and fell into swamps where they started to rot. The rotting trees were covered in sand and mud. Eventually the mud and sand were changed into rocks. Under the heat and pressure of the earth the rocks changed into rotting vegetation, first into peat and then into coal.

50
Q

Describe the formation of crude oil and gas:

A

Hundreds of millions of years ago organisms died and were covered b sand. The sand changed into sandstone and subjected the dead organisms to pressure and heat.

51
Q

What must crude oil go under for it to be useful?

A

Fractional distillation

52
Q

Describe what fractional distillation is:

A

Fractional distillation is the separation of crude oil into its component parts, or fractions. Chemical compounds are separated by heating them to a temperature at which one or more fractions of the mixture will vaporize.

53
Q

Describe what a fraction is:

A

A fraction in chemistry is a quantity collected from a batch of a substance in a fractionating separation process. In such a process, a mixture is separated into fractions, which have compositions that vary according to a gradient. A fraction can be defined as a group of chemicals that have similar boiling points.